Here that came up in my game today.... We had a monk using unarmed strike against the caryatid column, which has the special ability:
Shatter Weapons (Ex) Whenever a character strikes a caryatid column with a weapon (magical or nonmagical), the weapon takes 3d6 points of damage. Apply the weapon’s hardness normally. Weapons that take any amount of damage in excess of their hardness gain the broken quality.
So how does this affect the monk's fists? At the time I ruled ignored the special ability against the fists of the monk, but I am still unsure about this....